Can-out hatch assembly and positioning system

ABSTRACT

A can-out hatch assembly is adapted to engage in a sealed manner the upper end of a covered sealed container around an aperture in a sealed chamber and to remove the cover from the container permitting a contaminant to be transferred between the container and the chamber while isolating internal portions of the container and chamber from the surrounding environment. A swing bracket is coupled at a first end thereof to the inner, lower wall of the sealed container adjacent to the aperture therein. To a second end of the swing bracket is mounted a hatch cover which may be positioned in sealed engagement about the chamber&#39;s aperture by rotating the hatch cover in a first direction when the swing bracket is in the full down position. Rotation of the hatch cover in a second direction releases it from sealed engagement with the chamber&#39;s aperture. A lid support rod also coupled to the second end of the swing bracket and inserted through an aperture in the center of the hatch cover may be rotated for threadably engaging the container&#39;s cover whereupon the cover may be removed from the container and the hatch cover displaced from the aperture by pivoting displacement of the swing bracket. The contaminant may then be either removed from the container and placed within the sealed chamber, or vice versa, followed by positioning of the cover upon the container and the hatch cover over the aperture in a sealed manner.

CONTRACTUAL ORIGIN OF THE INVENTION

The United States Government has rights in this invention under ContractNo. W-31-109-ENG-38 between the U.S. Department of Energy and ArgonneNational Laboratory.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to but in no way dependent upon thefollowing application which is assigned to the assignee of the presentapplication and filed in the names of Robert C. Frank and Joseph C. Hoh:Serial No. 752415, filed July 3, 1985 and entitled "Can-Out HatchAssembly With Magnetic Retention Means".

BACKGROUND OF THE INVENTION

This invention relates generally to the handling of contaminants and isparticularly directed to an arrangement for transferring a contaminantbetween a sealed chamber and a closed container while maintaining thecontaminant isolated from the environment.

Toxic or radioactive contaminants are typically stored and transportedin sealed containers which prevent their escape into the surroundingatmosphere. Government regulations mandate that these containers bestructurally sound and leak proof. As a result, the greatest threat ofescape of a contaminant into the atmosphere generally occurs during thetransfer of the contaminant into or out of the container. During suchtransfers, it is absolutely essential that the inner, contaminated areasdefined by the contaminant-containing vessels be maintained completelyand permanently isolated from the outer, clean environment. This notonly requires the elimination of leaks from these vessels into thesurrounding environment, but also requires that any surfaces exposed tothe contaminants or contaminated atmosphere must not be exposed to thesurrounding environment. To date, no contaminant transfer arrangementhas been able to provide an effective, reliable seal during contaminanttransfer while preventing those portions of the transfer mechanismexposed to the contaminant from coming in contact with the surrounding,uncontaminated environment.

The present invention thus represents an improvement over the prior artin that it provides a safe, reliable and inexpensive arrangement fortransferring contaminated materials from a covered container to a sealedchamber, or vice versa, while limiting access to the contaminants andcontaminated atmosphere only to internal portions of the container andchamber to which the surrounding environment is not exposed.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to maintain acontaminant in isolation while transferring it between sealedcontainers.

It is another object of the present invention to provide an improvedarrangement for transferring a contaminant between sealed containerswhile preventing exposure of the atmosphere and outer parts of thecontainers to the contaminant.

Yet another object of the present invention is to provide a safe,reliable means for maintaining a contaminant in isolation whiletransferring it between closed chambers.

A further object of the present invention is to provide a can-out hatcharrangement particularly adapted for use with a radioactive hot cellhaving improved sealing and locking characteristics for maintaining acontinuous seal around the hot cell during the transfer of radioactivematerial into or out of the cell.

The present invention contemplates a can-out hatch assembly andpositioning system for transferring a contaminant between a sealedchamber and a closed container while maintaining the contaminantisolated from the environment which is particularly adapted for thehandling of radioactive materials. The hatch assembly includes anelongated swing bracket pivotally mounted at a first end thereof to aninner wall of the sealed chamber adjacent to an aperture therein throughwhich the contaminant is to be transferred. Secured to a second end ofthe swing bracket is a hatch cover adapted for positioning over theaperture in a sealed manner and including lid engagement means on alower portion thereof. Extending through the swing bracket adjacent tothe second end thereof and coupled to the hatch cover is a rotatableshaft. The lid engagement means extends downward from the hatch coverand includes a pair of pins adapted for insertion within respectivebores in the upper surface of the closed container's lid, or cover.Displacement of the rotatable shaft by means of an actuator arm coupledthereto causes rotation of the hatch cover and the pair of pinsextending downward therefrom as well as rotation of the closedcontainer's lid which is thereby released from sealed engagement withthe container.

Positioned within the rotatable shaft and extending the length thereofis a lid support rod which is threaded at a first, lower end and iscoupled to a control arm at the second, upper end thereof. The lower endof the lid support rod is adapted to engage a complementary threadedbore in the upper surface of the container's lid whereby the lid may beremoved from the container by pivoting displacement of the swing bracketaway from the chamber's aperture. The contaminant may then be movedbetween the chamber and the container without exposure to thesurrounding environment while the lower portion of the hatch cover,which includes the lid engagement means and is exposed to theenvironment following removal of the container, is shielded from thecontaminant by the container's lid. Both the actuator arm and controlarm may be manipulated by remote means within the sealed chamber and thecontaminant may be transferred by means of a remote manipulator. Theclosed container may be displaced and positioned over the sealedchamber's aperture by means of an automatic positioning system.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended claims set forth those novel features which characterizethe invention. However, the invention itself, as well as further objectsand advantages thereof, will best be understood by reference to thefollowing detailed description of a preferred embodiment taken inconjunction with the accompanying drawings, where like referencecharacters identify like elements throughout the various figures, inwhich:

FIG. 1 is a partially cutaway side view of a can-out hatch assembly foruse with a sealed chamber and a covered container in accordance with thepresent invention;

FIGS. 2a and 2b are a plan and a fragmentary sectional view of thecan-out hatch assembly of FIG. 1;

FIG. 3 is a partially cutaway plan view of a container with a cover foruse with the can-out hatch assembly of the present invention;

FIG. 4 is a partially cutaway lateral view of the covered container ofFIG. 3;

FIG. 5 is a lateral view of a container positioning assembly for usewith the can-out hatch assembly of the present invention; and

FIG. 6 is a plan view of the container positioning assembly of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, there are respectively shown a partiallycutaway lateral view and a plan view of a can-out hatch assembly 10 inaccordance with the present invention for use with a sealed chamber 14and a covered container 18. The sealed container 14 includes a pluralityof lateral panels, or walls, 15, an upper panel 16 and a bottom panel17. The bottom panel 17 includes an aperture 12 therein which is sealedby means of the can-out hatch assembly 10 of the present invention asdescribed below.

A remote controller 20 extends through a lateral panel 15 and into thesealed chamber 14 for manipulating the can-out hatch assembly 10 asdescribed below. The remote controller 20 is shown in simplifieddiagrammatic form in the figures and would typically include a pair ofmovable pincer elements 20a, 20b for grasping and manipulating thecan-out assembly. The remote controller 20 is typically subject tocontrol inputs provided by a user outside of the sealed chamber 14 andis capable of extension and retraction as well as elevational andlateral displacement within the sealed chamber to permit it to engagethe can-out hatch assembly 10 and exercise control over its operation.The remote controller 20 may also be used to transfer a contaminant (notshown) between the sealed chamber 14 and the container 18.

Briefly, under the control of the remote controller 20, the can-outhatch assembly 10 is capable of engaging the cover, or lid, 84 of thecontainer 18 when the container is positioned immediately adjacent toand aligned with the aperture 12 within the bottom panel 17 of thesealed chamber 14. The can-out hatch assembly 10 engages and removes thecover 84 from the container 18 and displaces it away from the aperture12 within the sealed chamber 14 to permit a contaminant to betransferred from the sealed chamber 14 to the container 18, or viceversa, while shielding the lower portion of the can-out hatch assembly10 from the contaminated environment within the sealed chamber 14. Oncethe transfer is completed, the cover 84 is again positioned in sealedrelation upon the container 18 by means of the can-out hatch assembly 10which is again positioned in sealed relation about the aperture 12within the sealed chamber 14. The covered container 18 with thecontaminant sealed therein may then be removed from the sealed chamber14, with the exposed lower surface of the can-out hatch assembly 10,which had been shielded from the contaminated environment within thesealed chamber, providing a "clean" surface to the surroundingenvironment. The can-out hatch assembly 10 of the present invention thusprovides for the sealed transfer of a contaminant between a sealedchamber and a covered container and ensures that no components orsurfaces of the contaminant transfer arrangement exposed to thecontaminant are later positioned in contact with the surroundingenvironment. The details of the manner in which this is accomplished bythe can-out hatch assembly of the present invention are provided in thefollowing paragraphs.

The can-out hatch assembly 10 includes an elongated swing bracket, orpivot arm, 22 pivotally coupled to the bottom panel 17 of the sealedchamber 14 by means of the combination of a hinge base, or pivotbracket, 24 and a hinge shaft, or pivot pin, 28. The pivot end 22a ofthe swing bracket 22 is pivotally coupled to the hinge base 24 by meansof the pivot pin 28. The hinge base 24 is securely mounted to the uppersurface of the bottom panel 17 of the sealed chamber 14 by means of amounting screw 26. As shown in FIG. 2, a hinge base 24 is positionedimmediately adjacent to the pivot end 22a of the swing bracket 22, withthe pivot end 22a adapted to engage the pivot pin 28 substantially alongthe entire length thereof. The swing bracket 22 is thus adapted forrotational displacement about the pivot pin 28 to allow for the raisingand lowering of the swing bracket 22 within the sealed chamber 14.

The second end of the swing bracket 22 is provided with first and secondrotational displacement limiting apertures 72, 74 and yet anotheraperture within which is positioned a generally cylindrical hub 30. Thehub 30 extends upward from the swing bracket 22 and is orientedgenerally 90° with respect thereto. The hub 30 and the swing bracket 22may be coupled by conventional means such as by welding.

Positioned within the hub 30 and free to rotate therein is a shaft 32.The shaft 32 is coupled at its upper end to a generally horizontallyoriented actuating arm 54 and at its lower end to a generally planarhatch plate 55. The rotatable shaft 32 may be coupled to the actuatingarm 54 and hatch plate 55 by conventional means such as welding,coupling pins, etc. Positioned within the rotatable shaft 32 and, inturn, free to rotate therein is lid support rod 34. The lid support rod34 includes a threaded portion 38 at the lower end thereof adapted toengage a threaded bore 40 in the upper surface of the container's cover84. The upper end of the rotatable lid support rod 34 is coupled to acontrol arm 44 by means of a roll pin 46. A control knob 48 is mountedto the distal end of the control arm 44 by means of a shoulder screw 50which is maintained in place by a roll pin 52. A thrust washer 47 ispositioned around the upper end portion of the rotatable shaft 32 and isinterposed between the actuating arm 54 and hub 30 to facilitaterelative rotation therebetween. In addition, a washer 49 is positionedbetween the swing bracket 22 and the hatch plate 55 to facilitaterotational displacement therebetween. This configuration of componentspermits the hatch plate 55 to be rotationally displaced by engaging anddisplacing the actuating arm 54. Similarly, the lid support rod 34including the threaded lower end portion 38 thereof may be rotationallydisplaced by displacement of the combination of the control arm 44 andcontrol knob 48. As stated above, the control knob 48 and actuating arm54 are adapted for engagement and rotational displacement by the remotecontroller 20.

A first spring 42 is positioned about an upper end portion of the lidsupport rod 34 and between the control arm 44 and the rotatable shaft32. Similarly, a second spring 43 is positioned around the lid supportrod 34 and between the rotatable shaft 32 and a retaining ring 36located on a lower portion of the lid support rod. The first spring 42biases the lid support rod 34 upward while the second spring 43 biasesthe lid support rod downward and, in combination, maintain the lidsupport rod firmly positioned within the hub 30 and adapted for engagingthe cover 84 of the container as described below.

Positioned around the periphery of the hatch plate 55 are a plurality ofslots 65. Located in the periphery of the hatch plate 55 immediatelyadjacent to each of the slots 65 is a camming surface 58 which isinclined relative to the generally flat upper surface of the hatchplate. Securely mounted to the upper surface of the bottom panel 17 ofthe sealed chamber and positioned around the periphery of the hatchplate 55 in spaced relation are a plurality of locking assemblies 60.Each of the locking assemblies 60 is positioned around the periphery ofthe hatch plate 55 so as to coincide with a respective slot 65 therein.Each locking assembly 60 includes a lock down bracket 62 secured to thebottom panel 17 of the sealed chamber by means of mounting screws 64 and66. Securely coupled to each of the lock down brackets 62 is a threadedlock down pin 68 which extends through and below a lower portion of thelock down bracket 62. The lower end portion of each of the lock downpins 68 is adapted to engage a respective camming surface 58 of thehatch plate 55 when the hatch plate is rotated in a counterclockwisedirection as shown in FIG. 2. This provides for the downwarddisplacement of the hatch plate 55 and its secure engagement with thebottom panel 17 of the sealed chamber. Rotational displacement of thehatch plate 55 is accomplished by rotating the actuating arm 54 which iscoupled to the hatch plate 55 by means of the rotatable shaft 32. Forillustration purposes, hatch plate 55 is shown in the downward lockedposition in FIG. 1 but in the unlocked position in FIG. 2.

First and second limit pins 56, 57 are threadably positioned within arespective aperture within the hatch plate 55. In addition, the upperend portions of the first and second limit pins 56, 57 are positionedwithin first and second rotational displacement limiting apertures 72,74, respectively, within the swing bracket 22. The combination of theaforementioned limiting pins 56, 57 and limiting apertures 72, 74 servesto limit the rotational displacement of the hatch plate 55 relative tothe swing bracket 22. With a respective limit pin 56, 57 positioned atone end of a rotational displacement limiting aperture 72, 74, the hatchplate 55 is positioned in the full down position and in sealedengagement with the bottom panel 17 of the sealed chamber. Similarly,with each of the limit pins positioned at the other end of a respectivelimiting aperture, the hatch plate 55 is disengaged from the bottompanel 17 and also from each of the locking assemblies 60 allowing thehatch plate to be pivotally displaced above the bottom panel and awayfrom the aperture 12 therein by means of the swing bracket 22. It is inthis manner that by rotational displacement of the hatch assembly 55 bymeans of the actuating arm 54, the hatch plate may be locked in sealedengagement with the bottom panel 17 of the sealed chamber and may alsobe released therefrom to permit the hatch plate to be removed from theaperture 12 in the sealed chamber to permit transfer of a contaminantinto or out of the sealed chamber.

A compressible outer gasket, or O-ring, 59 is positioned on the lower,peripheral surface of the hatch plate 55 for engagement with the bottompanel 17 to provide sealed contact therebetween. Similarly, acompressible inner gasket, or O-ring, 61 is also positioned on the lowersurface of the hatch plate 55 for effecting sealed engagement betweenthe hatch plate and the container cover, or lid, 84 as described below.

Referring to FIGS. 3 and 4, there are respectively shown partiallycutaway plan and side views of a container 18 having a cover, or lid, 84thereon. Each of the first and second limit pins 56, 57 extends belowthe lower surface of the hatch plate 55 and is adapted for insertionwithin a respective bore 88, 90 within the upper surface of thecontainer's cover 84. In addition, a threaded bore 40 in the center ofthe top surface of the container's cover 84 is adapted to receive andengage the threaded lower end portion 38 of the rotatable lid supportrod 34. Positioned around the periphery of the container's cover 84 isan O-ring 86 which is adapted to engage in a sealed manner the innersurface of the container 18 when the cover is positioned tightlythereon. Positioned around the periphery of and inserted through thelateral surface of the container 18 are a plurality of locking pins 82.The outer periphery of the cover 84 is similarly provided with aplurality of generally L-shaped locking notches 94 which are spacedaround the periphery of the container's cover similar to the spacedarrangement of the locking pins 82 around the container itself. Eachlocking notch 94 is adapted to receive a respective locking pin 82 whendisplaced downward upon the upper edge of the container 18 and includesa sealing rib 92. Rotation of the container's cover 84 in the directionof the arrow shown in FIG. 4 results in engagement of the locking pin 82with the sealing rib 92 whereupon the cover 84 is locked in sealedengagement with the container 18. Rotation of the cover 84 in theopposite direction unlocks the cover and permits it to be removed fromthe container 18.

Installation and removal of the cover 84 on the container 18 by thecan-out hatch assembly 10 is accomplished in the following manner.Before the container 18 is placed in position adjacent to the aperture12 within the bottom panel 17 of the sealed chamber 14, the hatch plate55 is positioned in sealed engagement with the sealed chamber's bottompanel as shown in FIG. 1. The container 18 is then positioned in sealedengagement with the lower gasket 63 on the lower surface of the bottompanel 17 immediately adjacent to and around the aperture 12 therein asshown in FIG. 1. With the container 18 thus positioned in engagingcontact with the lower gasket 63 on the bottom panel 17, the threadedbore 40 in the center of the cover 84 is aligned with the threaded lowerend portion 38 of the rotatable lid support rod 34. Similarly, the firstlimit pin 56 is inserted in the first bore 88 and the second limit pin57 is inserted in the second bore 90 in the upper surface of thecontainer's cover 84. Sealed engagement between the cover 84 and thecontainer 18 is maintained by the O-ring 86.

Rotation of the lid support rod 34 results in engagement between thethreaded lower end portion 38 thereof and the threaded bore 40. Rotationof the lid support rod 34 causes the upward displacement of the cover84, the upper peripheral surface of which is then engaged by the innergasket 61. The lower surface of the hatch plate 55 is thus isolated fromthe contaminant within the container 18 when the cover 84 is removedtherefrom. Rotation of the actuating arm 54 causes the rotation of thehatch plate 55 and first and second limit pins 56, 57 coupled theretoand results in the rotational displacement of the cover 84. When thecover 84 is rotated in a direction generally opposite to the directionof the arrow shown in FIG. 4, each of the locking pins 82 becomesdisengaged from a respective sealing rib 92. Rotation of the actuatingarm 54 similarly unlocks the hatch plate 55 from engagement with thebottom panel 17 of the sealed chamber 14 as previously described. Withthe cover 84 thus unlocked from the container 18 and engaged by thethreaded lower end portion 38 of the lid support rod 34 and the hatchplate 55 thus unlocked from the bottom panel 17, the actuating arm 54may be engaged by the remote controller 20 and displaced upward to allowthe pivoting displacement of the swing bracket 22 about the pivot pin28. The hatch plate 55 as well as the container's cover 84 may thus beremoved from the aperture 12 within the bottom panel 17 and thecontaminant may either be removed from the sealed chamber 14 and placedin the container 18 or vice versa.

Once the contaminant is thus transferred, the combination of the hatchplate 55 and cover 84 is again positioned within the aperture 12 of thebottom panel 17. The hatch plate 55 may then be locked in positionagainst the bottom panel 17 and the cover 84 may be locked in sealedengagement with the container 18 by rotating the actuating arm 54. Withthe hatch plate 55 positioned in sealed engagement with the bottom panel17 of the sealed chamber 14 and the cover 84 securely positioned uponthe upper edge portion of the container 18, the lid support rod 34 maythen be rotated by means of the control knob 48 to permit disengagementof the lower threaded portion 38 of the lid support rod from thethreaded center bore 40 in the upper surface of the container's cover84. The sealed container 84 may then be removed from engagement with thelower surface of the bottom panel 17 with the hatch plate 55 remainingin sealed engagement about the aperture 12 within the bottom panel ofthe sealed chamber 14.

Referring to FIGS. 5 and 6, there are respectively shown lateral and topplan views of a container positioning assembly 100 for use inpositioning the container 18 around the aperture 12 in the chamber'sbottom panel 17 and in sealed engagement therewith. The containerpositioning assembly 100 includes a frame 102 coupled by means ofmounting bolts 104 to the bottom panel 17 of the sealed chamber andsuspended therefrom. A lower portion of the frame 102 includes agenerally horizontally aligned base 106. Mounted upon the base andextending generally vertically upward therefrom are a pair of alignmentrods 110. Also positioned upon the base 106 of the frame is thecombination of an electric motor 114 and a scissors frame 118. Theelectric motor 114 is coupled to the scissors frame 118 by means of athreaded shaft 116 such that rotation of the shaft in one directioncauses the upward extension of the scissors frame, while rotation of thethreaded shaft in the opposite direction results in the retraction, ordownward displacement, of the scissors frame. Coupled to an upperportion of the scissors frame 118 and aligned with the alignment rods110 is a support platform 108. The support platform 108 is free to movevertically along the alignment rods 110 and is supported by the scissorsframe 118. Positioned on an upper surface of the support platform 108 isa generally circular alignment ring, or rim, 112. The covered container18 is positioned within the alignment ring 112 which is positionedwithin the container positioning assembly 110 such that upwarddisplacement of the support frame 108 positions the upper end of thecovered container 18 in tight fitting relation with the bottom panel 17of the sealed chamber and about the aperture 12 therein.

The alignment ring 112 includes an alignment slot 122 therein which isadapted to receive an alignment bracket 96 positioned on the lateral,outer surface of the covered container 18. The alignment bracket 96,which is shown in greater detail in FIGS. 3 and 4, is positioned by thealignment ring 112 for maintaining proper alignment between the coveredcontainer 18 and the sealed chamber 14. By thus maintaining properalignment between the sealed chamber 14 and the covered container 18,the bores 88, 90 within the upper surface of the container's cover 84are maintained properly aligned with the first and second limit pins 56,57 within the hatch plate 55. Thus, when the covered container 18 ispositioned over the aperture 12 in the bottom panel 17 of the sealedchamber, the container's cover 84 will be positioned and oriented topermit the can-out hatch assembly of the present invention to engage,rotate, and remove the cover from the container as described above.

As shown in FIG. 6, the container positioning assembly 100 may be partof a conveyor system 120 which displaces the sealed containers to aposition immediately beneath the aperture within the sealed chamber foreffecting the transfer of contaminants therebetween. The combination ofthe conveyor system 120 and the container positioning assembly 100affords fully automatic transport and positioning of the coveredcontainers for improved reliability and safety in the transfer ofcontaminants.

There has thus been shown a can-out hatch assembly and positioningsystem for facilitating the transfer of a contaminant between a sealedchamber and a covered container which allows for removal of thecontainer's cover while maintaining sealed engagement between thecontainer and the sealed chamber about an aperture therein. The exteriorportion of the hatch assembly is covered by the container's lid and thusshielded from the contaminant during its transfer. Therefore, when thehatch assembly is again positioned over the chamer's aperture, thechamber is again sealed with respect to the surrounding environment andthe exterior surface of the hatch assembly remains "clean", not havingbeen exposed to the contaminant during its transfer. Provision is madefor remote operation of the hatch assembly as well as for the automatictransport and positioning of the covered container in alignment with theaperture within the sealed chamber.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from theinvention in its broader aspects. For example, while one specificarrangement for engagement of the container's cover by the can-out hatchassembly has been shown and described in detail, a large variety ofcoupling arrangements, some of which would not require alignment betweenthe container's cover and the hatch assembly and which are conventionalin design and operation, would be available to and are known by thoseskilled in the art. In addition, other forms of remote control meansother than a mechanical arm such as shown and described herein could beused for manipulating the can-out hatch assembly of the presentinvention. Many such control systems, such as of the pneumatic orhydraulic type, could be utilized in the present invention and areconventional in design and operation and thus could be easily integratedfor use in the present invention by those skilled in the relevant arts.Therefore, the aim in the appended claims is to cover all such changesand modifications as fall within the true spirit and scope of theinvention. The matter set forth in the foregoing description andaccompanying drawings is offered by way of illustration only and not asa limitation. The actual scope of the invention is intended to bedefined in the following claims when viewed in their proper perspectivebased on the prior art.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A hatch assembly forsealing an aperture within a wall of a sealed chamber in a first closedposition while permitting the transfer of a contaminant between saidchamber and a container positioned in sealed engagement with said wallaround the aperture therein in a second open position, said containerhaving a cover positioned in sealed engagement thereon, said hatchassembly comprising:an elongated member pivotally mounted at a first endthereof to an inner surface of the sealed chamber's wall and having asecond end positioned over the aperture in the wall when said elongatedmember is in a first lowered position; rotational displacement meanscoupled to said elongated member adjacent to the second end thereof; agenerally planar member coupled and responsive to said rotationaldisplacement means and positioned over the aperture in the wall whensaid elongated member is in said first lowered position, wherein saidplanar member may be rotationally displaced by said rotationaldisplacement means; locking means mounted to the inner surface of thewall for locking said planar member in sealed engagement with the wallabout the aperture therein when said planar member is rotated in a firstdirection and for releasing said planar member from the wall when saidplanar member is rotated in a second direction by said rotationaldisplacement means; connecting means mounted to said elongated memberadjacent to the second end thereof for coupling said elongated member tothe cover of the container when the container is positioned in sealedengagement with the wall around the aperture therein; and engaging meanscoupled to said planar member and rotationally displaced therewith bysaid rotational displacement means for engaging the cover of thecontainer when positioned in sealed engagement with the wall around theaperture therein, wherein rotation of said engaging means in said firstdirection locks the cover in sealed engagement with the container androtation of said engaging means in a second direction disengages thecover from the container permitting the cover to be removed from thecontainer by said connecting means when said elongated member ispivotally moved to a second upraised position and wherein the cover ispositioned over the lower surface of said planar member in shieldingsaid planar member's lower surface from exposure to the contaminant. 2.A hatch assembly in accordance with claim 1 further comprising, incombination, a pivot pin and a pivot bracket coupling the first end ofsaid elongated member to an inner surface of the sealed chamber's wall.3. A hatch assembly in accordance with claim 1 further comprising remotecontrol means within the sealed chamber for displacing said elongatedmember between the first lowered position and the second upraisedposition.
 4. A hatch assembly in accordance with claim 1 wherein thesecond end of said elongated member includes an aperture wherein arepositioned said rotational displacement means and said connecting means.5. A hatch assembly in accordance with claim 4 wherein the container'scover includes a threaded bore in an upper surface thereof and whereinsaid connecting means includes a rotatable shaft having a threaded lowerend portion for threadably engaging the cover.
 6. A hatch assembly inaccordance with claim 5 wherein the upper surface of the container'scover is generally circular in cross-section and said threaded bore ispositioned generally in the center of the upper surface of the cover. 7.A hatch assembly in accordance with claim 6 further including a controlarm coupled to an upper end portion of said rotatable shaft tofacilitate the rotational displacement thereof.
 8. A hatch assembly inaccordance with claim 7 further comprising first biasing means coupledto said rotatable shaft for urging the lower threaded end portionthereof in an upward direction when the cover is disengaged from thecontainer by said engaging means.
 9. A hatch assembly in accordance withclaim 8 further comprising second biasing means coupled to saidrotatable shaft for urging the lower threaded end portion thereof in adownward direction when the cover is positioned in sealed engagementwith the container to facilitate engagement of the lower threaded endportion of said rotatable shaft with said threaded bore in the cover.10. A hatch assembly in accordance with claim 9 wherein said first andsecond biasing means each include a coiled spring positioned on saidrotatable shaft along a portion of the length thereof.
 11. A hatchassembly in accordance with claim 1 wherein the second end of saidelongated member includes an aperture therein and said rotationaldisplacement means includes a generally vertical shaft positioned withinthe aperture of said elongated member.
 12. A hatch assembly inaccordance with claim 11 further including an actuating arm coupled toan upper end portion of said vertical shaft to facilitate the rotationthereof.
 13. A hatch assembly in accordance with claim 1 furtherincluding rotation limiting means coupled between said elongated memberand said planar member for limiting the rotational displacement of saidplanar member between first and second positions, wherein said planarmember is in sealed engagement with the chamber's wall when in saidfirst position and is disengaged from the chamber's wall in said secondposition.
 14. A hatch assembly in accordance with claim 13 wherein saidelongated member includes a pair of slots therein and said rotationlimiting means includes first and second pins coupled to said planarmember and positioned within a respective slot in said elongated memberand wherein the ends of said slots define the limits of the rotationaldisplacement of said planar member.
 15. A hatch assembly in accordancewith claim 14 wherein said engaging means includes a pair of spacedbores on an upper surface of the container's cover and respective lowerend portions of the first and second pins which are adapted forinsertion within a respective spaced bore to facilitate rotation of thecover by said rotational displacement means.
 16. A hatch assembly inaccordance with claim 1 further including a compressible seal positionedbetween said planar member and the chamber's wall around the aperturetherein.
 17. A hatch assembly in accordance with claim 1 furtherincluding a compressible seal positioned between said planar member andthe container cover around the periphery thereof.
 18. A hatch assemblyin accordance with claim 1 further including a compressible sealpositioned between an upper edge portion of the container and a lowersurface of the chamber's wall around the aperture therein.
 19. A hatchassembly in accordance with claim 1 wherein said planar member isgenerally circular and includes a plurality of paired slots and adjacentcam surfaces around the periphery thereof and wherein said locking meansincludes a plurality of brackets spaced around the periphery of saidplanar member and mounted to the inner surface of the wall and adaptedto engage a respective cam surface when said planar member is rotated insaid first direction.
 20. A hatch assembly in accordance with claim 1further including positioning means for maintaining the container insealed engagement with the wall around the aperture therein during thetransfer of the contaminant between the chamber and the container andfor aligning the container with said hatch assembly to facilitateengagement of the container's cover by said engagement means.
 21. Ahatch assembly in accordance with claim 20 wherein said positioningmeans includes an alignment bracket positioned on an outer surface ofthe container and a receptacle for receiving the container, wherein saidreceptacle includes a notch in a lateral portion thereof for receivingsaid alignment bracket.
 22. A hatch assembly in accordance with claim 21further including conveyor means for translationally displacing thecontainer to a position immediately beneath the aperture within thechamber's wall.